Ultra high frequency power oscillator



April 13, 1948. c. E. HALLMAR K ULTRA HIGH FREQUENCY POWER OSCILLATOR Filed Dec. 29, 1944 3 Sheets-Sheet l INVENTOR CLYDE E. HALLMARK ATTORNEY- April 13, 1948.

C, E. HALLMARK ULTRA HIGH FREQUENCY POWER OSCILLATOR Filed Dec. 29, 1944 5 Sheets-Sheet 2 FIG? INVJEN'TOR LLMARK CLYDE E.HA

ATTO R N EY April 13, 1948. c. E. HALLMARK ULTRA HIGH FREQUENCY POWER OSCILLATOR Filed Dec. '29, 1944 3 Shee t sSheet 3 OUTPUT OUTPUT KNVENTOR CLYDE E. HALLMARK 'ATTORNEY Patented Apr. 13, 1948 ULTRA H FREQUEN PO R SCILLATOR Glyde E. Hallmark, Fort Wayne, Ind., assignor,

by mesneassignments, to Farnsworth Research Corporation, acorporation of Indiana Application December 29, 1344, s rial No. 570,256

This invention relates to electric discharge devices and particularly to an oscillator capable of generating ultra-high frequencies.

Numerous oscillators have heretofore been devised for generating high and ultra-high irequencies. In a well known system the oscillations generated by a regeneratively coupled amplifier are stabilized by a timed circuit. Instead of a feedback amplifier an electron discharge tube having a negative resistance may be utilized for generating oscillations. The tuned circuits associated with a feedback amplifier or a negative resistance discharge device usually comprise lumped reactance elements such as capacitances and inductances, the values of whichdetern ine the resonant frequency. A tuned circuit of this type is quasi-stationary, that is, at any given instant the oscillating current intensity in the tuned circuit is the sameat any point because the current oscillates back and iorth between the capacitance element and the inductance element. However, in such an oscillatorsystem the values of the component parts of the circuit place an upper limit on the frequencies that can be generated therein.

In order to increase the frequency which can be generated by an oscillator it has been suggested to employ resonant transmission lines as tuned circuits. Such a resonant transmission line is also known in the art as a Lecher wire system. A tuned circuit of this type is non-stationary, that is, the current intensity at a certain instant is different at different points of the tuned circuit. A tunedtransinission line does not possess discontinuities such as lumped capacities and, therefore, standing wavesare 'developed so that at a certain point of the line a voltage node is formed while other portions .of the tuned circuit have voltage rnaXima or ventral segments. Oscillators associated witha tuned transmission line or Lecher wire system have considerable merit. They may be used for-generating ultra-high frequencies, such for example as those of the'order of three thousand megacycles. However, great difliculties' have been ex.- perienced heretofore in order to devise oscillators of this type which have an appreciable power output at ultra-high frequencies.

Another drawback of conventional oscillators associated with a tuned transmission line is that a discontinuity is introduced into the system at the junction of the oscillator tube and the transmission line. This drawbackhas led to the development of special ftlube iorms to obviate or minimize such discontinuities.

16 Claims. (01. 250-275) It is an object of the-present invention, therefore; to provide an oscillator capable of generating ultra-high frequencies with a substantial power output. A further object of this invention is to provide an oscillator where the frequency of oscillation is determined by the physical dimensions-of the oscillator tube. i

Another object of the invention is to provide an oscillator circuit which does not possess any discontinuitiessuch as lumped capacities.

Still another object of theinvention is to provide an oscillator tube structure which requires a minimum of electric leads that have-to be sealed through the evacuated .envelopeoi the tube.

In accordance with the present invention there is provideda highr vacuum electron discharge device comprising an outer hollow member .of conducting material. At least one pair .ofinner members of conducting material is provided. The inner members are insulated from each other and disposed within the outer member. The-inner members have substantially equal length and one of each pairoi inner members has a grid-like extension at each :end thereof surrounding; a; portion oi the .other one of the pair of inner meme bers; Means coextensive with the grid-like tensions are provided for emitting electrons. Each oithe gridqlike extensions and the portions of the outer and inner members 'coei ztens e therewith serve as a three-element vacuum a, .while the intermediate sections of the m; serve as transmissiolllin thi manner 9. or morepairs of threeeelement yacuumtubes are provided.

Preferably, the cu er membe i o toroida shape and serves as a cathode. Qne of each p "r .of innerme bers serve a a r d, whi the. other on uof each pai of i e m mb r S s a anode. The length ofeach of the inner members may be substantially equal to one-half the wave length of the waves tobe generated.

For a better understanding of the invention, together with other and. further objects thereof, reference is made to the following description, taken in connection with the a'ccompanyingd-rawings, and its scope will be pointed out inth'e appended claims.

In the accompanying drawings:

Fig. 1 is'a'plan view, partly in section, of an electric discharge device embodying the present invent on;

Fig. 2 is .across sectional view along line 2-=-.2 of Fig. 1;

Fig. 3 is a cross-sectional view along line 33 of Fig. 1;

Fig. 4 is a plan view similar to Fig. 1 showing means for fluid cooling the anode structure of the discharge device;

Fig. 5 is an electric circuit diagram of the oscillator of Fig. 1 and its connections; I

Fig. 6 is a diagram of the equivalent electric circuit of the oscillator of Fig. 1;

Fig. '7 is a plan view, partly in section, of a modified electric discharge tube in accordance with the invention containing two pairs of three element vacuum tubes;

Fig. 8 is a schematic electric circuit diagram of the oscillator of Fig. 7; and

Fig. 9 is a diagram of the equivalent electric circuit of the oscillator of Fig. 7.

Referring more particularly to Figs. 1 to 3 of the drawings, there is provided a high vacuum electron discharge device i6 including an outer member ll of toroidal shape which preferably serves as the cathode of the discharge device. Two inner members l2 and 3 are provided within cathode H extending substantially through the entire length of cathode Inner member l2 preferably serves as the anode of electric discharge device iii, and member l3 serves as the grid thereof. Anode I2 is hollow and'closed at both ends as clearly shown in Fig. 1. Grid |3 has two perforated or grid-like extensions 14 and I5 which surround a portion of each end of anode l2 and which may, for instance, consist of a wire screen. The inner surface of cathode member I6 is provided with electron emissive material at Hi and I1. Electron emissive surfaces i6 and ll are coextensive with perforated or gridlike extensions l4 and I5, respectively. Heater windings l8 and 26 are arranged outside of cathode member H for heating electron emissive surfaces l6 and H in order to provide a copious electron flow.

Cathode member ll may be made of glass and may have an inner surface of electrically conducting material such as a metal film. Alternatively, cathode member may be made of metal. Anode member |2 and grid member l3 preferably consist of a metal of good electric conductivity such as copper or silver. Due to the skin effect, high frequency current is localized within a very thin surface layer of the conducting line. Hence, it is only necessary to plate the outer surface of inner members l2 and I3 and the inner surface 'of cathode member H with copper or silver for the purpose of reducing the electric resistance thereof. Lead 2| connected to the mid-portion of anode member I2 is sealed through cathode member II by means of insulating seal 22. Lead 23 is connected to the midportion of grid member -l3 and sealed through cathode member H by insulating seal 24. Output leads 25, 25, sealed through cathode member H by insulating seals 27, 21, are connected to loop 26' inductively coupled to the mid-portion of anode member l2.

Referring now to Fig. 4, there is illustrated means for fluid cooling the electric discharge device shown in Fig. 1. For this purpose anode member |2 is provided with fluid inlets 36, 3| and a fluid outlet 32. The cooling fluid may be introduced through inlets 36, 3| and may be removed from outlet 32. It will be understood that anode member I2 is closed and fluidtight. Inlets 30, 3| and outlet 32 are connected to suitable pipes sealed through outer cathode member The pipe connections between anode l2 and cathode member 3 should be electrically insulated.

Referring now to Fig. 5, there is shown a schematic electric circuit diagram illustrating the circuit connections of the oscillator structure shown in Figs. 1 to 4. Electric discharge device It of Figs. 1 to 4 is electrically equivalent to two threeelement vacuum tubes 35 and 36. The plates of tubes 135 and 36 are connected by lead 31, the two grids are connected by lead 38 and the oathodes are connected by lead 40, grounded as shown. Lead 31 and the plates of vacuum tubes 35, 3% correspond to anode member l2 shown particularly in Fig. 1. Similarly, lead 38 and the grids of vacuum tubes 35, 36 correspond to grid member |3 and its extensions l4, l5; lead 43 and the two cathodes of tubes 35, 36 correspond to cathode'member H. For the purpose of applying positive operating potential to the plates of tubes 35,36 lead 2| connects the mid-portion of lead 31 through resistor 4| 'to battery 22 having its negative terminal grounded. Bypass condenser 43 connects lead 2| to ground. For applying negative operating potential to the grids of tubes 35, 36 there is provided lead 23 connecting the mid-portion of grid lead 38 through resistor 44 to battery 45 having its positive terminal grounded. Bypass condenser 46 connects lead 23 to ground. Battery 142 supplies a positive potential to the plates of tubes 35, 36 which may be of the order of magnitude of 1000 volts, while battery 45 supplies a negative potential of the order of magnitude of volts to the grids of tubes 35, 36.

The operation of the oscillator of the invention will readily be understood with reference to Fig. 6 showing the equivalent circuit of the oscillator structure. The cathodes of tubes 35, 36 are grounded and the grids thereof are connected in phase opposition. Hence, tubes 35, 36 are arranged in push-pull. Tuned circuit 50 is connected by leads 5|, 5| to the plates of tubes 35, 36; Another tuned circuit 52 is connected by leads 53, 53 to the grids of tubes 35, 36. Tuned circuit 53 corresponds to the tuned transmission line represented by anode member I2. The distributed capacitance and inductance of the tuned transmission line as well as the interelectrode grid-to-plate capacitances have been represented by the lumped capacitance element and inductance element of tuned circuit 56 in'Fig. 6. Similarly, tuned circuit 52 corresponds to the tuned transmission line represented by grid member l3 and grid-like extensions l4, l5. The distributed capacitance and inductance of the tuned transmission line as well as the interelectrode cathode-to-grid capacitances have been shown in tuned circuit 52 of Fig. 6 as a condenser and coil. Lead 2| supplies positive operating potential from a battery indicated schematically at 3+ to the mid-portion of the inductance coil of tuned circuit 56. Lead 23 supplies negative operating potential from a battery B- to the midportion of the inductance coil of tuned circuit 52. The ultra-high frequency output energy is derived from leads 25, 25 connected to loop 26 coupled, in turn, to the inductance coil of tuned circuit 56.

It will be seen that the oscillator circuit of Fig. 6 is a push-pull connected tuned-grid tuned-plate oscillator. In order to tune the transmission lines represented by tuned circuits 5!) and 52, anode member l2 and grid member |3 each have apgaunt proximately {the same "length corresponding to on half-th'ewave length of the oscillations to be generated. Accordingly, parallel resonant circuits 5'0 and-5'2 are tuned to approximately the same freque'nby.

The operation of a tuned-grid tuned-plate oscillator is well understood in the art, and will be explained here for an oscillator having one tube-only. The coupling between the plate cirfruit and the grid circuit of the oscillator is effected through the tube. This electronic type of coupling can be explained in the following manner. If the frequency of the plate circuit is below its resonant frequency, the plate load is inductive. Hence, thegrid-to-plate interelectrode capacitance results in a negative value of the effective conductance between the grid "and the cathode. It can be shown that for an inductive load the grid conductance is negative, in other words, the circuitoperates similar to a negative resistance device. Therefore, instead of dissipating power throughthe oscillator tube, power is supplied from the tube into the grid circuit as well as into the plate circuit.

It follows from the above explanation that the parallel resonant plate circuit of a tuned-grid tuned-plate oscillator should have a resonant frequency which is slightly higher than the resonant frequency of the parallel resonant grid circuit. Only when this condition is met, the effective conductance between the grid and the cathode has a negative value which is essential for the operation of the oscillator. Hence, the effective electrical length of anode member 12 should be slightly less than the effective electrical length of grid member IS. The effective length of grid member l3 should be calculated from the mid-portions of extensions. M and I5. Therefore, it will be seen that, although the physical length of anode member l2 and grid member is may be substantially equal, the effective electrical length of anode member I2 is slightly less than that of grid member I3 dueto the extensions M and I5 of ano de 12; which is just what is required, because a shorter electrical length of anode member l2 will slightly increase the resonant frequency of the parallel resonant circuit in series with the anodes.

The operation of a push-pull connected tunedgrid tuned-plate oscillator will be obvious from the explanations given hereinabove. As clearly shown in Fig. 6 the grids of tubes 35' and 36 are connected in phase opposition. Therefore, when either tube 35 or tube 36 is conducting space current the other one is inoperative and vice versa. Therefore, voltage maxima or antinodes are devcloped at the end of portions of anode member 52 and-grid member l3. The thus produced oscillations will develop standing waves along anode member [2 and grid member I3, and it is obvious that voltage nodes are formed at the mid-portions of anode member l2 and grid member IS. The standing voltage waves in turn creat standing oscillatingc'urrent waves which have a 90 degrees phase shift in space with respect to the standing voltage waves. Accordingly, current maxima are developed at the mid-portions of anode member l2 and grid member l3. The direct current potentials are connected to those points of anode member [2 and grid member l3 where the alternating current waves have their maxima. Output loops 26 is arranged where the alternating current of anode member l2 has its maximum.

The physical length of anode memberlZ and grid "member [3, therefore, determines the nequency of the oscillator circuit. Hence, it is feasibleto generate micro-waves down to a wave length ofone decimeter corresponding to a frequencyof up to 3000 megacycles, The lower limit of the frequency to be generated or, in other words, the upper limit of the wave length depends upon the physical dimensions of the discharge devicejand may be of the order of magnitude of one meter corresponding to 300 megacycles.

The power output obtainable with the oscillator of the invention is high even at a low wave length of about 10- to 15 centimeters. Anode member l2 and grid member I3 are in the form of a transmission line and, therefore, they can be made with a high Q, that is, with a high ratio of reactance to resistance and, hence, the losses in the circuit are very low. Furthermore, the oscillator of the invention has a high symmetry andthe transmission lines are arranged in such a manner that no discontinuities are introduced. These factors coupled with the comparatively great heat dissipating power of anode member l2 and cathode member I!) all contribute to a high power output of the oscillator.

When the frequency to be generated by the oscillator of the invention becomes very high or the wave length very short, the dimensions of the tube become very small, In this case it may be advantageous to employ more than the equivalent of one pair of three-element vacuum tubes.

Such a structure has been illustrated in Fig. '7. As shown in Fig. '7, there is provided a high vacuum electron discharge tube 55 having an outer member 56 of toroidal shape which preferably serves as a cathode. Within cathode member 56 there are disposed two anode members 51 and 58'and two grid members 60 and 6!. Grid member 66 is provided with two grid-like extensions 62 and 53 of wire mesh which surround adjacent end portions of anode members 51 and 58, respectively. Grid member Bl also has two grid-like exensions E4 and '55 surrounding the other end portions of anode members 58 and 51, respectively. Electron emissive materials 66, 61, 68 and it, arranged on the inner surface of cathode member 56, are provided coextensive with each grid-like extension 62, 63, 64 and 65. For the purpose of heating electron emissive surfaces 05, 67, 68 and 10, heater windings H, (-2, l3 and '54 are arranged about cathode members 56.

Leads 15 and F6 are connected to the midportions of anode members 5? and 58, while leads fl and is are connected to the mid-portions of grid members 60 and iii, respectively. Leads 15, it, I? and it are sealed through cathode member 56 by insulating seals 80. Cathode member 55 may either be of glass with an inner metal film such as copper or silver or it may consist of metal. Anode members 5?, 58 and grid members 6% 6! preferably consist of metal which may be copper or silver plated as explained in connection with Fig. 1. If desired, anode members 5? and 58 may be fluid cooled in the manner shown in Fig. 4.

The electrical connections of electron discharge device 55 of Fig. 7 are illustrated in Fig. 8. Anode members BI, 82, shown schematically in Fig. 8, have their mid-portions connected to anode transmission line 53, while grid members 84 and 85 have their mid-portions connected to grid transmission line 6%. Positive operating potential 82 and grids 84, 85 have approximately the same length corresponding to one-half the wave length I electrical length of grid members 60 and 5| will behigher in view of their extensions 62, 63, 64 and 65.

Theeffective length of anode transmission line 83 from either anode 8| or anode 82 to lead 8'! is equal to one-half the wave length of the waves to be generated or a multiple thereof. Grid transmission line 85 preferably has the same lengthas anode transmission line 83 so that its effective length from either grid 84 or grid 85 to lead 88 is equal to one-half the wave length of the oscillations or a multiple thereof.

When oscillations are generated by the oscillator shown in Figs. 7 and 8, standing waves are generated along anodes til, 82 and grids 84, 85. Due to the fact that anodes 8|, 82 and grids B4, 85 have an effective length approximately equal to one-half of the wave length to be generated, voltage nodes are developed at the mid-portions of anodes 8!, 82 and grids 8d, 85. Similarly, the free ends of anodes 8|, t2 and grids 8d, 85 have voltage maxima or 'antinodes. The standing waves of the current developed by the standing voltage waves have a phase displacement of 90 degrees in space with respect to the standing voltage waves, and, therefore, current maxima are developed at the mid-portions of anodes 8|, 82 and grids 8a, 85. The mid-portions of trans" mission lines 83 and 86 correspond electrically to the mid-portions of anodes 3!; S2 and grids B4,

85, respectively. Hence, the direct current is supplied to those points of transmission lines 83 and 86 where the alternating current has a maximum. The oscillating output energy is derived from output terminals 9%), 90 connected to loop 9| which is coupled'to the mid-portion of anode transmission line 83.

The equivalent electric circuit of the oscillator of Figs. 7 and 8 is illustrated in Fig. 9. The circuit includes four three-element vacuum tubes e2, 93, wand 95. Vacuum tubes 82 and 93 arranged in push-pull with their cathodes grounded have a tuned grid circuit 95 and tuned-plate circuit 9?. Vacuum tubes 94, 95 also arranged in push-pull with their cathodes grounded have a tuned-grid circuit 98 and a tuned-plate circuit lili). As explained in connection with Figs. 1 to 6, tuned circuits 96, 9?, 98 and I98 represent the distributed capacitances and inductances of anode members 57, 58 and grid members 60, 5| as well as the interelectrocle capacitances of the four vacuum tubes. Tuned grid circuits 96 and 98 have the mid-portions of their inductances coupled by tuned circuit ifll corresponding to grid transmission line 86. The negative potential from a battery indicated at B is supplied to the grids of the four tubes by lead 88. Since tuned circuit iii! corresponds to transmission line 83 there is actually a conductive connection between the battery B and the grids of the four tubes, although in Fig. 9 series condensers have been shown in tuned circuit lill.

Similarly, tuned circuit 582 corresponding to anode transmission line 83 interconnects the mid-portions of the inductances of tuned circuits 91 a d, l -.,-L. 1.8 s pp es po v volta fromba ttery 13+ to the mid-portion of the in duct'ance; of tuned circuit I QZ. As explained teammate; there is a conductive connection from battery 3+ to the anodes of the four tubes, although series condensers areshown in tuned circuit 162. The oscillating output energy is obtained through leads 90, 9B connected to loop 9|, which in turn is coupled to the inductance of tunedcircuit I02- This circuit operates similarly to. the circuit shown in Fig. 6 and, therefore, no. further explanation is needed here.

The discharge device shown in Fig. 1 comprises only four wires which have to be sealed through cathode member ll. Also, in the discharge device shown in Fig, '7 only four wires have to be sealed in which greatly simplifies the glasswork. 4

' Outer toroidal member ll of the oscillator of Figs. I to 4 and outer'mer'nber 56 of the discharge device of Fig. '7, preferably, are used as the cathodefof. the discharge device. This has the advantage that since the cathode is grounded, the discharge device is 'at' ground potential. Another advantage is that the heater windings or the equivalent of the'filament heater system maybe arranged outside oftoroidal member H or 56 and, hence, need not be sealed through the outer member of the" discharge device. Furthermore, by" using the 'outertoroidal member I I or 56 as the cathode the cathode emission is increased. However, for the operation of: the oscillator of theinventio'rrit is entirely immaterial whether the outer member is the cathode or the anode. If outer member H of Figs. 1 to 3 is used as the anode, inner member l2 should be used as the cathode. s 7

It is also feasible to utilize the electron dis char'ge device'fof the invention as a push-pull amplifier in the ultra-highfrequency field. For

this purpose it is necessary to neutralize the interelectrode capacitances of the two discharge paths of the device shown in Figs. 1 to 4 or of the four discharge paths of the discharge device of Figs. '7 and 8 so that self-oscillation is prevented. This canbe done, for instance, by cross-connecting the grid of each tube structure to the plate of the other tube structure through a condenser which will neutralize the interelectrode capacitances of the discharge paths. The operation ofa push-pull'neutralizing circuit of this type is well understood in the art and, hence, no further explanation is required here.

While there has been'described' what are at present considered the preferred embodiments of theinvention, it will be obvious to those skilled inth'e art that various changes and modifications may be made therein without departing from the inventiom'and it is, therefore, aimed in the appendedjclaims to cover all suchchanges and modifications'as fall within the true spirit and scope of the inventionl What is claimed is:

1. A' high vacuum electron discharge device comprising .an outer hollow member of conducting material, at least one pair of inner members ofconducting material insulated from each other and disposed within said outer member, said inner members having substantially equal length, one of said inner members having an electron controlling extension at each end thereof surrounding a portion of the other one of said pair of inner members, and electron emitting means coextensive with said extensions, each of said extensions and the portions of said members coextensive with said extensions constituting .a three.- element vacuum tube with the intermediate secti'ons of said members constituting transmission lines.

2. A high vacuum electron discharge device comprising an outer hollowand closedmember of conducting'material serving as a cathode, two inner members of conducting materialinsulatcd from eachother and disposed within said outer member, said inner members having substantially equal length, one of saidlinner members serving as a grid and the other one as ananode, each one of said grid members having a grid-like extension at each end thereof surrounding a portion of the adjacent anode member and electronemitting means along the inner, surface ofsaid oath? ode and coextensive with said, grid-like. extensions, each of said extensions and the portions of the adjacent anode member and said cathode member coextensive with said extensions constituting a three element vacuum tubewith the intermediate sections of said members constituting transmission lines.

3. A high vacuum electron discharge device comp-rising an outer member of conducting material having a toroidal shape and serving as a cathode, at least one pair of inner members of con ducting material insulated. from each other'and disposed within said outer member, said inner members having substantially equal length, one of saidinner members serving as a grid andthe other one as an anode, each one of said grid meme bers having a grid-like extension at each end thereof surrounding a portion of the adjacent anode member, each of said anode members being closedat its ends to form a fluid tight structure, means extending through said cathode member for circulating a cooling fluid through said anode member, and electron emitting means extending along saidgrid-like extensions, each of said extensions and the portions ,ofthe aclja cent anode member and said cathode member coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constitutingtransmission lines.

4. A. high vacuum electron discharge device comprising anouter member of conducting material having a toroidal shape andserving as a cathode, atleast one ,pair of inner members of conducting material insulated from each other and disposed within said outer member, said inner members having substantially equal length and forming together substantially a torus, one of said inner members serving a grid and the other one as, an anode, each one of said grid members having a grid-like extension at each end thereof surrounding a portion of theadjacent anode member, electron emissive surfaces extending on the inner surface of said cathode member along said grid-like extensions, and means outside of said cathode member for heating said electron emissive surfaces, each of said extensions and the portions of the adjacent anode member and said cathode member coextensive with said extensions constituting a three-element vacuum tube withthe intermediate sections of said members constituting transmission lines.

5. A high vacuum electron. discharge device comprising an outermemberof conducting material having a toroidal shape and serving as a cathode, at least one pair of inner members of conducting material insulated from each other and extending substantially through the entire 10 inne lengthof said outer member, oneof said ne ns-me t e v n a a i ml h ther one asan anode, each one of said grid members having a grid-like extension ateach end thereof surrounding a portion of g the adjacent anode member, electron emissive surfaces extending on the inner surface of said cathode member-along said grid-like. extensions, and heater windings outside of said cathode members for heating said electron emissive surfaces, each ofsaidextene sion at each end-thereof surrounding a portion of the other one of said inner members, and electron emitting meansextending along said extensions, each of said extensionsand the portions ofsaid members coextensive with said extensions constituting a three-elementvacuumtube with the intermediate sections of said members constituting transmission lines 7. A high vacuum electron dischargedevice comprising an outer hollow and closed member of conducting material serving as a cathode, two inner. members of conducting material insulated from each other and disposed within said outer member, said two inner members having substantially equal length, one of said inner members serving as a grid and the other one as an anode, said grid member having a grid-like extension at each end thereof surrounding a portionof said anode member, and electron emitting means along the inner surface of said cathode member-and coextensive with said grid-like extensions, each of said extensions and the portions ofsaid anode and cathode members coextensive with saidextensions constituting a three-element vacuumtube with the intermediate sections of said ,members constituting transmission lines. 8, A; high vacuum electron discharge device comprising an outer member of conducting ma-,

terial h'avinga toroidal shape and serving as a cathode, two inner members of conducting material insulated from each other and disposed within said outer member, said two inner members havingsubstantially equal length, each of 1 said two inner members extending substantially through a semicircle, oneof said inner members serving as a grid and the other one as an anode, saidgrid member having a grid-like extension at each endthereof surrounding a portion of said'anode member, said anode member being closed .at its ends to form a fluid tight structure, means extending through said cathodemember forcirculating a cooling fluid through said anode member, and electron emitting means extending along said grid-like extensions, each of said extensions and the portions of said anode and cathode members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting transmission lines.

9. A high vacuum electron discharge device cathode, two inner members of conducting ma- 11 terial insulated from each other and disposed within said outer member, said two inner members facing each other and having substantially equal length, one of said inner members serving as a grid and the other one as an anode, said grid member having a grid-like extension at each end thereof surrounding aportion of said anode member, electron emissive surfaces extending on the'inner surface of said cathode member along said grid-like extensions, and means outsideof said cathode member for heating said electron emissive surfaces, each of said extensions and the portions of said anode and cathode members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting transmission lines.

' 10.'A high vacuum electron discharge device comprising an outer member of conducting material having a toroidal shape and serving asa cathode, two inner members of conducting material insulated from each other and disposed within said outer member, said two inner members having substantially equal lengthand extending substantially through the entire inner length of said outer member, one of said inner members serving as a grid and the other one asan anode, said grid member having a grid-like extension at each end thereof surrounding a portion of said anode member, electron emissive surfaces extending on the inner surface of said cathode member along said grid-like extensions, and heater windings outside of said cathode member for heating said electron emissive surfaces, each of said extensions and the portions of said anode and cathode members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting transmission lines.

ll. An oscillator for generating ultra-short waves comprising an outer hollow member of conducting material, at least one pair of inner members of conducting material insulated from each other and disposed within said outer member, said inner members having substantially equal length corresponding to substantially one-half the wave lengthof the waves to be generated, one of said inner members having a grid-like extension at each end thereof surrounding a portion of the adjacent inner member, and electron emitting means extending along said grid-like'extensions, eachof said extensions and the portions of said members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of saidmembers constituting resonant transmission lines.

12. An oscillator for generating ultra-short waves comprising an outer member of conducting material having a toroidal shape and serving as a cathode, at least one pair of inner members of conducting material insulated from each other and disposed within said outer member, one of said inner members serving as an'anode and the other-inner member serving as a grid, said inner members having substantially equial'leng'th corresponding to substantially one-half the wave length of the waves to be generated, each of said grid members having a grid-like extension at each end thereof surrounding a portion of the adjacent anode member, electron emitting means'along the inner surface of said cathode member and coextensive with said grid-like extensions, said cathode member being connected to ground, and means for supplying suitable potentials'coupled to the mid-portions of said grid members and of said 12 anode members, each of said extensions and the portions of said anode and cathode members c0- extensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting resonant transmission lines whereby said mid-connection points become voltage nodes and the end portions of said anode and grid members voltage maxima.

13. An oscillator for generating ultra-short waves comprising an outer member of conducting material having a toroidal shape and serving as a cathode, at least one pair of inner members of conducting material insulated from each other and disposed within said outer member, one of said inner members serving as an anode and the other inner member serving as a grid,said inner members facing each other and having substantially equal length corresponding to substantially one-half the wave length of the waves to be generated, each of said grid members having a gridlike extension at each end thereof surrounding a portion of the adjacent anode member, electron emissive surfaces along the inner surface of said cathode member and coextensive with said gridlike extensions, heater windings outside of said cathode member for heating said emissive surfaces, said cathode member being connected to ground, means for supplyingsuitable potentials coupled to the midvportions of said grid members and of said anode members, and means coupled to said anode member for deriving oscillating output energy of a wave length determined by the length of said inner members ,"each of said extensions and the portions of said anode and cathode members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting resonant transmission lines, said mid-connection points becoming voltage nodes and the end portions of said grid and anode members voltage maxima, thereby to provide a push-pull connected tuned-grid tuned-plate oscillator.

14. An oscillator for generating ultra-short waves comprising an outer, hollow and closed member of conducting material, two inner members of conducting material insulated from each other and disposed within said outer member, said inner members having substantially equal length corresponding to substantially one-half the wave length of the waves to be generated, one of said inner members having a grid-like extension at each end thereof surrounding a portion of the other one of said inner members, and electron emitting means extending along said grid-like extensions, each of said extensions and the portions of said members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting resonant transmission lines.

15. An oscillator for generating ultra-short waves comprising an outermember of conducting material having a toroidal shape and serving as a cathode, two inner members of conducting material insulated from each other and disposed within said outer member, one of said inner members serving as an anode and the other one as .a grid, said inner members forming together substantially a torus and having substantially equal length corresponding to substantially one-half the wave length of the waves to be generated, said grid member having a grid-like extension at each endthereof surrounding a portion ofsaid anode member, electron emitting means along the inner surface of said cathode member and coextensive with said grid-like extensions, said cathode memher being connected to ground, and means for supplying suitable potentials coupled to the midportions of said grid member and of said anode member, each of said extensions and the portions of said anode and cathode members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting resonant transmission lines whereby said mid-connection points become voltage nodes and the end portions of said grid and anode members voltage maxima.

16. An oscillator for generating ultra-short waves comprising an outer member of conducting material having a toroidal shape and serving as a cathode, two inner members of conducting material insulated from each other and disposed within said outer member, one of said inner members serving as an anode and the other one as a grid, said inner members extending substantially through the entire inner length of said outer member and having substantially equal length corresponding to substantially one-half the wave length of the waves to be generated, said grid member having a grid-like extension at each end thereof surrounding a portion of said anode member, electron emitting means along the inner surface of said cathode member and coextensive with said grid-like extensions, said cathode member being connected to ground, means for supplying suitable potentials coupled to the mid-portions of said grid member and of said anode member, each of said extensions and the portions of said anode and cathode members coextensive with said extensions constituting a three-element vacuum tube with the intermediate sections of said members constituting resonant transmission lines, whereby said mid-connection points become voltage nodes and the end portions of said anode and grid member voltage maxima, and a loop at the node of said anode for deriving oscillating output energy of a wave length determined by the length of said inner member, thereby to provide a pushpull connected tuned-grid tuned-plate oscillator.

CLYDE E. HALLMARK.

REFERENCES CITED The following references are of record in the file of this patent:

, UNITED STATES PATENTS Number Name Date 1,979,668 Boddie Nov. 6, 1934 1,981,058 Marconi et a1 Nov. 20, 1934 2,153,728 Southworth Apr. 11, 1939 

